Telephone-relay.



PATENTED JULY 21, 1908. G W UNDERWOOD.

TELEPHONE RELAY. AI-PPLIUATION FILED FEB. 6, 190B. 2 SHEETS SHEET 1.

avwemtoz N 893 95s. PATENTED JULY 21 1908.

0 0. W. UNDBRWOOD.

TELEPHONE RELAY.

' APPLIG IIIIIIIIIIIIIIIIII a.

uveul'oz MW W/WM UNITED srnrjgsggrnnr OFFICE.

CHARLES W. UNDERWO'OD, OF CROWTZEY, L 'JISIANA.

TELE HONE-RELAY.

Specification of Letters Patent.

Patented Jul 21 1908.

Application filed. February 6, 1908. Serial No. 414,596.

This invention has reference to improvements in telephone relays whereby electrlcal undulations passing over a hne and. acting upon a telephone receiver will be converted into mechanical vibrations which in turn are caused to act upon a nncrophom'c orloose contact transmitter element whereby thereis setup in the second circuit electrical undulations corresponding to those generated in the first circuit, which undulations are of increased amplitude or strength. The electrical undulations in the second circuit may be either transformed into air vibrations at a distant telephonic receiver or may be converted into other electrical undulations corresponding to the original undulatlons in v still a third circuit, and so on.

. The present invention is an improvement over that set forth in my application, Serial #382,475, for telephone relay, filed July 6, 1907.

.' The present invention relates more particularly to improvements in the means for causing mechanical vibrations in the microphonic or loose contact transmitter element and the conversion of these mechanical vibrations into electrical undulations in the second line circuit.

In accordance with the invention set forth 'in my aforesaid application, the electrical undulations in the first circuit are caused to act upon an armature mounted upon a tightly-stretched support secured to the armature by a connection of small area, the point of connection being centralized to the magnetic field of the receiver. The armature is made light and the support for the same may be made of tightly stretched wires radiating from a circumscribed and central-I ized point of connection made as small as possi-ble, and the armature is connected to a telephonic transmitter element so that the impulses imparted to the armature by the telephonic receiver are caused to act upon the transmitter element in such manner that increased electrical venerg may be thrown upon the second line in t ie-form of electrical undulations 'correspondingto all of the char-1 acteristics of the original undulations. The armature is balanced in a magnetic field while the supports for the same, preferably in the form of fine wires or thin narrow metallic ribbons are under critical,longitudinal stress, the connection with the armature or with the armature carrier being midway between the ends of these wires'or ribbons and centralized with relation to the magnetic field. "ith such means I have found that there is a very marked increase in the effect upon the armature of the electrical undulav tions acting on the receiver, and this effect is sufiiciently energetic to roduce in the transmitter element a su cient amplitude of movement to cause electrical undulationsv upon the second line far in excess of the undulations reaching the telephone receiver.

In accordance with the present invention there are provided two receiving elements which may be similar to the ordinary telephonic receiver except that the diaphragms are replaced by light armatures, and these armatures are supported in a centralized osition with relation to the magnetic fiel ofthe respective receiver by means of tightly stretched Wires or thin bands. Each of the two receivers are spaced apart with their polar ends facing each other, and the armatures are connected to opposite sides of a transmitter element or transmitter elements in multiple, the point of connection from each armature being at that side of the transmitter remote from the receiver.

There are also other features of the present invention wherein it differs from the invention' set forth in my aforesaid application,

which, together with the principal features of detail description taken in connectionwiththe accompanying drawings forming a part of this specification, in which d rawings- Figure 1 is a plan viewof that portion of the relay. structure including the improvements forming the subject-matter. 'of the. present invention and so much of; the coact ing structure as is necessary;- Fig. 2 is a side elevation of the structure shown in Fig. 1. Fig. 3 is a diagrammatic view of. thelcircuit connections. Figs. 4 to 7"'-are,detail views.

The relay structure com'rises two" like parts, one intended for the re ay of electrical undulationscomihg from one direction and the other intended for therelay of electrical standards 2, 3, each formed of a post with anextended slotted base 4 through each of which there is passed a fastening screw 5, whereby the standards may be adjusted in any direction upon the'base. Each standard carries a microphonic element 6, which may comprise a suitable cylinder having flexible ends terminating in connecting posts 7,, The

interior of the microphonic or transmitter element is filled with carbon granules to a necessary extent.

Mounted on the base board on each side of the transmitter element and spaced therefrom, are short posts 8 each carrying fast thereon or, if desired, formed thereon a ring 9 which should be made of some good conducting metal. At four equidistantpoints each ring 9 is tapped radially for the reception of screw plugs 10 having a radial perforation 11 for the reception of one end of a wire 12, the said wire being heldv in a counterbored portion of the plug by any suitable means, as by a pin or by turning the end of the Wire on itself or in any other suitable manner, Which will permit the plug 10 to be turned on its axis Without twisting the wire. The four plugs 10 carry two wires 12 crossing each other at the center of the ring 9, and these wires may be 'put under longitudinal strain by screwing the plugs 11 radially outward into the ring 9. It is possible to use but two plugs and one wire extending diametrically across the ring, or more than two wires may be used, the number of plugs being correspondingly increased. Nor is it necccssary that there should be rings 9 employed-since these rings may be replaced by frames of any other shape than circular.

Attached to each stem 7 of the transmitter element by a suitable nut 13 is the leg 14 of a corulecting bar 15, the latter being at right angles to the leg 14 so as to override the trai'ismitter element 6 and extend in a direc tion away from the post 7 to which the leg 14 is connected. The free end of the bar 15 has formed on it or attached to it a head 16 in which there is formed two diametric grooves 17 crossing each other at right angles. The two wires 12 already referred to pass through these grooves and are crossed. The head 16 is tapped centrally at the crossing point of the two grooves 17 and there receives the threaded stem 18 of a disk 19. stem serves to connect the disk 19 to the head 16 and at the same time firmly unite the two wires 12 to the said head 16.

The disk 19 with its stem 18 may be made of iron or other magnetic material, while the head 16 and arm 15, as well as the ring '9, may be made of some non-1nag11etic material,

ous results. The threaded but good conducting material, such as phos phor bronze or copper or other suitable metal. The wires 12, which, as will be understood, may be replaced by thin narrow ribbons or bands, or other filamentary means, may be made of steel upon which copper may be electrically deposited and the copper maybe plated if desired with silver or other material, the purpose being to unite the tensile strength of steel with the conducting qualities of copper or silver, since, as will presently appear, these wires are designed to carry the currents.

On the base 1 on that side of each ring 9 remote from the transmitter element 6, there is secured a hollow post 20 provided with a set screw 21, and this hollow post receives a stem 22 split longitudinally to receive an arm 23 carrying at its outer enda ring 24. The arm 23 is held to the stem 22 by a pivot pin 25, while a thumb screw 26 serves. to hold the arm 23 in any adjusted position about the pin 25. The ring 24 is provided with an internal screw thread and into this fits a block 27 externally threaded and carry ing the magnetic element 28 of an ordinary telephone receiver, this element being made up, as is usual, of apermanent magnet with soft iron pole pieces surrounded by the usual coils 29. The rear ends of the telephone eleo ments 28 may be provided with suitable casings 30, and the entire structure, except the casings 30 and those parts inclosed therein, may be covered by a glass case 31 which of course may be replaced by any other material, such for instance, as hard. rubber, and if desired the cover 31 may be so made and attached to the, base that the air may be exhausted therefrom so that the inclosed parts operate in a vacuum.

It has before been stated that the wires 12 may be made ofasteel core and be. plated with copper or silver or both, or infact with any other good conducting material. A cross section of one of these wires is shown in Fig. 5, where the steel core is indicated at 32 and the covering of metal of higher conductivity, is indicated at 33. These wires are thus composite wires having sufficient tensile strength for the purpose and at the same' time are of sufficiently high conductivity.

, It is of advantage to have the transmitter element of as low resistance as possible in order that it may carry a heavy current and it should be so constructed that it may carry the desired heavy current without deleteri- For this purpose the transmitter element may be doubled, asindicated in Fig. 7 where there are two transmitter elements 6 having the like ends of their posts 7 joined together by straps 34, and these straps are connected to the arms 14 of the bars 15, so that each late 19 is connected to the like ends or headsof two transmitter elements 'in multiple.

When the parts are properly assembled receiver elements is permitted to a nicety by v the pivoted arm 23 and the post 22, together with the fastening devices for each of these structures. The screw plugs 10 are adjusted until the Wires 12 are brought into acritical state of longitudinal strain, and the head 16 is clamped to these wires by means "of the screw stem 18 on the armature 19, the adjustments being such that the crossing of the two wires and their connection to the armature is circumscribed within a very small area, and is carefully centralized in the mag netic field of the receiver element. The magnetic 'pull of the'receiver magnets upon each armature is resisted by the microphonic or transmitter element and the-whole structure is adjusted until these pulls and strains are all at the critical point. The rings 9 are joined in pairs by insulating connecting rods 35. i Y

The circuit connections which may be employed are shown in Fig. 3. Here 1t will be assumed that two line conductors 36 and 37 will be the line coming from or leading to a distant station and two other line conductors 38 and 39 also represent the line leading to or coming from another distant station, and between these two stations is located the telephone relay forming the subject-matter of the present invention. The conductors 36 and 37 lead to the fine wire winding of an. in-,

duction coil 40 and the conductors 38 and 39 lead to the .fine wire winding of another induction coil 41. Theconductor.36.or 37 leads by branch conductors 42 and 43 to the coils 29 of two of the receiver elements 28 arranged in line one with the other and together acting on one of the transmitter elements 6 or on a pair of the same where a single transmitter element is replaced by a mechanically connected pair of elements. Incoming currents over the conductors 36 and 37.will act simultaneously on the coils. 29 and cause the receiver magnets to simultaneously attractor repel the corresponding armatures 19, thus moving the heads of the transmitter elements toward or from each other, as the case may be.

The simultaneous movement of the heads of the transmitter element will set up therein large variations of resistance, which variations correspond to the electrical impulses coming over the line. One ring 9 of the pair of rings under consideration is connected by a conductor 44 to the coarsewire winding of the induction coil 41, While the other ring 9 is connected-to the coarse wire winding of the induction coil 41, by a conductor 45', and this conductor includes a suit able battery 46 or other source of electric current. g

The variations of the resistance set up in the transmitter element 6 will of course roduce like variations in the local circuit inc uding the battery 46, and these variations will set up on the line conductors 38 and 39 augmerited im ulses corresponding to the electrical impu ses coming over the conductors 36 and 37.

The conductor. 38 or '39 is connected by other conductors 47 and 48 tothe coils 29 of the other receiver elements 28, the said coils being connected in series, and the other transmitter element 6 is connected by a conductor 49 to one side of the coarse wire winding of the induction coil 40, and to the other side ofthe coarse wire winding of the in duction coil 40 by another conductor '50, in which latter conductor is included a battery 51. By this means there is an outgoing and return pat between two distant telephone stations, and in. this path ment are acted on'simultaneously by the receivers,.the movement of these transmitter elements is double that which would occur Were they acted upon on one side only by a single receiver, and consequently the disturbance of theearbon granules and the variations of resistanceis correspondingly greater.

When two transmitter elements are used together and mechanically connected so as to be simultaneously acted upon. by the two receiver elements connected in series, then a heavier battery current may be used because of the lower resistance of the path of the battery current through the transmitter elements, and the effect upon the line upon which the local circuitacts iscorrespond ingly augmented.

In order to counteract the normal magnetic 1111 of the magnets each bar 15 may be provic ed with a cross arm 52, and these cross arms are connected with elastic strands 53,

which may be in the form of suitable springs,

rovided both normal magnetic pull of the magnets on the,

arm-atures so that these armatures are 1n 9.

state of substantial equilibrium.

Whatis claimed is 1. In a telephone relay, two telephone receiver magnets with their coils connected in series, a telephonic transmitter, an armature inoperative relation to each telephone receiver magnet and mechanically connected to the transmitter element on the side thereof remote from the armature, and filamentar sup orts for each armature having a loca 1Z8 extremities facing but spaced from the polar extremities of the first-named ma net, a transmitter element between the po ar extremities of the magnets, armatures, one for mg a localize longitudinal strain.

each receiver magnet, connections between each armature and that side of the transm1t-' ter element remote from the armature, and filamentary su ports for-each armature havsaid filamentary supports being under initial 3. In a telephone relay, a telephone re ceiver magnet and coils, another telephone receiver magnet and coils, armatures one for each receiver magnet and in operative relation thereto, a filamentary support for each armaturehaving a localized central connection thereto, and means for putting said sup ports under longitudinal strain, means for centering the armature to the polar extremities of the respective receiver magnets, a

transmitter element common to both receiver elements, and connections from each armature to the transmitter element on the side of the latter remote from the respective armature.

4. In a telephone relay, a telephone receiver magnet and coils, another telephone receiver magnet and coils, a support for each receiver magnet adjustable both longitudi ation tov the length of the mag net and at right angles thereto, an armature -45 nally with re for each receiver magnet, a support for each armature comprising a suitable frame, metal filaments supported by the framela'nd carrying said armature, means carried by the frame and engaging the filaments for putting the latter under longitudinal strain, a telephonic transmitter, and connections be tween each armature and that side of the transmitter remote from the said armature.

central connection thereto,

5. In a telephone relay, two opposed tele- 1 phone receiver magnets and coils, with the coils connected for simultaneous action, an armature for each receiver magnet, a sup port for each armature having a localized central connection thereto andnnder initial longitudinal strain, a transmitter element, and connections between each armature and said transmitter element for action thereon simultaneously in opposite directions.

6. In a telephone relay, two opposed re ceiver magnets and coils, an armature for each receiver magnet, a filamentary sup ort for the armature under initial longitu ianl strain and having a localized central connec tion'to the armature, atransmitter element, and means for causing the armatures to act simultaneously in opposite directions on said transmitter element.

ceiver elements, armatures there or, a tele ically connected transmitter elements acting in multiple, and connections between the armatures and the telephonic transmitter on the sides of the latter remote from the ro- Spective armature for acting on the said transmitters simultaneously in opposite directions.

8. In a telephone relay, two telephone rcceivers ino posed relation one to the other, arma tures for said receivers, metallic' filamentary supports for said armatures, means for putting said supports under initial longi tudinal strain, metallic frames for the lilamentary supports, a transmitter element, metallic connections between the armatures of the receiver magnets and the ends ofthe receiver elements remote from the respective armature, circuit connections includmg the coils of both telephone receivers, and a local charged circuit including the transmitter element, the frames, the filamentary supports and the connections from the armatures to i the said transmitter element.

In testimony that I claim the foregoing as my own, I have hereto affixed my signature in the presence of two witnesses.

CHARLES WV. UNDERWOOD.

l/Vitnesses:

JAs. M. WALKER, NM. J. NEALE.

7. In a telephone relay, two 0 posed re phone transmitter made up of two mechan-. 

